Explicație:
1) c=20%
ms=500 g
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md=?
m apă=?
c/100=md/ms=>20/100=md/500=>md=20×500/100=10 000/100=100 g
m apă=ms-md=500 g-100 g=400 g
2) c=1%
ms=250 g
--------------
md=?
m apă=?
c/100=md/ms=>1/100=md/250=>md=1×250/100=250/100=2,5 g
m apă=ms-md=250 g-2,5 g=247,5 g
Succes!